Asphalt shearing process



United States Patent 3,511,769 ASPHALT SHEARING PROCESS Luke W. Corbett,382- Short Drive, Mountainside, NJ. 07092, and George A. Clarke, Jr.,910 Ripley Ave., Westfield, NJ. 07090 No Drawing. Continuation-impart ofapplication Ser. No. 740,492, June27, 1968. This application May 15,1969, Ser. No. 825,026

Int. Cl. Cc 3/00, 3/04 U. Cl. 208--39 9 Claims ABSTRACT OF THEDISCLOSURE Industrial grade asphalts are produced by subjectingpetroleum residua or asphalt fluxes to very high rates of shear in thepresence of air and/or nitrogen oxides or inert atmosphere. v T-CROSS-REFERENCES TO RELATED APPLICATIONS This application is acontinuation-in-part of copending application, Ser. No. 740,492, filedJune 27, 1968.

BACKGROUND OF THE INVENTION Field of the invention Description of theprior art In conventional methods of refining petroleum, a largefraction is often obtained as the residue from distillation of petroleumcrude oils. This fraction generally is referred to as the residuum, oras it has also come to be known, asphalt flux. This latter terminologyindicates the principal effectiveness of this fraction as a startingmaterial in the preparation of asphalt products. A number of techniquesare known for producing asphalts of varying physical properties fromasphalt flux. These include vacuum distillation, with or without thepresence of steam, air blowing at elevated temperatures, and chemicaltreatment.

In general, the conventional asphalt conversion processes possess one ormore inherent disadvantages. For example, the air-blowing of asphaltfiux usually involves a batch operation which requires the use of bulkyexpensive equipment for long periods of time. Furthermore, the softeningpoint-penetration relationship of air-blown asphalt frequently is notsuitable for use in many possible applications. Similarly, steam orvacuum distilling of asphalt flux produces a relatively hard asphaltwhich is too temperature sensitive to be useful in many asphaltapplications. The chemical treatment of asphalt flux may also beundesirable since it usually involves the use of expensive chemicalsand/or the use of critical process control.

SUMMARY OF THE INVENTION In accordance with the invention, ithas nowbeen found that improved asphaltic products are prepared by means of aprocess which comprises subjecting petroleum residuum or asphalt flux tohigh shearing forces for short 3,511,769 Patented May 12, 1970 periodsof time at elevated temperatures in the presence of air and/or nitrogenoxides or inert atmosphere. As will be shown hereinafter, the intenseshearing of the asphalt flux results in new and unexpected qualitieswhich are not due merely to the increased contact of the asphalt withair or chemicals. Thus, although the mechanisms involved in the methodof the invention are not fully understood, it is believed that thesubstantial improvements produced such as higher softening points for agiven penetration level are due to the creation of reactive sites byscission of asphaltic material, which reactive sites enable thesematerials to combine in some manner to produce asphaltene-typecomponents.

Suitable nitrogen oxides include, among others, nitric oxide (NO),nitrous oxide (N 0), nitrogen dioxide (N0 nitrogen pentoxide (N 0 andmixtures thereof The preferred nitrogen oxide is nitrogen dioxide. Gaseous mixtures of air and nitrogen oxides in any relative proportions mayalso be used.

The petroleum residuum or asphalt flux utilized in the process of thisinvention may vary considerably de pending upon the particular crude oilused, especially upon its geographic origin. Thus, some crude stocks wilyield much larger proportions of residuum than others and there may beinherent variations in chemicals com position as well. The chemicalidentity of these residua however, is not important with respect to thesuccess 0: the process of this invention, and it is'unnecessary itbecome concerned about the differences in such chemica identities. Theseresidua are conveniently defined i1 terms of softening point and flashpoint. As a practica matter, the residua are characterized by an ASTIVsoftening point value of at least about 60 F., preferably within therange of from F. to about F., am a Cleveland Open Cup flash point above400 F. Sucl limits define the range of commercially available straighrun petroleum residua adapted for use in this process Non-limitingexamples of residua suitably employed an derived from Lagunillas, TiaJuana, Boscan, Aramco Talco, Kuwait, Oregon Basin, Lloydminister, Sant:Maria, Kern River, Eucutta and Safanyia crudes, ant the like.

As used herein, the term shearing is intended it include any method forsubjecting the asphalt flux it shearing forces, that is, the applicationof force in shearing plane. In a preferred embodiment, asphalt materials are forced to pass through a restricted openin; where they aresubjected to intense forces of impact ant hydraulic shear. Examples ofapparatus suitable for sucl purposes are: the Eppenbachhomogenizersmixer mad and sold by Gifford-Wood, Inc., the Charlottemill, th Gaulin homogenizers made and sold by the Manton GaulinManufacturing Company, the Morehouse mil made by Morehouse Industries,and other similar ap paratus suitable for the purpose.

The amount of hydraulic shear or shearing stress t be applied to thepetroleum residuum or asphalt flux wil vary over a. considerable rangedepending upon the initia softening point of the asphalt flux,and thetime and/o temperature of application, etc., but it should be at leassufficient to effect an increase in the softening point 0 the asphaltflux, and preferably suflicient to increase th softening point of theasphalt flux at least 40%.

The rate of shear is preferably above 4000 reciproce seconds, and stillmore preferably above 25,000 reciproca seconds, e.g., 40,000-500,000reciprocal seconds. In thi connection, since the rate of shear isdirectly proportiona to the diameter of the rotor operating within astate and inversely proportional to the clearance between roto andstator, the upper limit of shear rate is depender upon practical, sizingof the shearing apparatus. Conceh it is possible to go to much higherrates of shear shearing forces) although'the practical objectives 11Sinvention may be satisfied by shear rates herein ribed.

1e shear stress may be applied by any suitable means :mperatures whichmay be, for example, within the e between about 300 and 600 F.,preferably 400 550 F., for a period of time ranging from a few ltes toseveral hours. Preferably, the high shearing will be applied for 10-100minutes, more preferably minutes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS series of runs were made inwhich a Lagunillas ght reduced petroleum flux having a softening point)3 -F. and a penetration of 182 at 77 F. was sub- :l to various shearingrates in a conventional Eppenhomogenizer which is described in detail inWet ng and Homogenizing Equipment, pp. 12-14, Catalo. 600, issued byGifford-Wood, Inc. (1957). Brieftandard laboratory unit (model l-LHomo-Mixer) used wherein mixing-homogenizing is carried on by :rsing aturbine-stator head in a mixing container. In rtion, the turbine rotatesat a speed that develops a ure difier'ential' between the bottom of theturbine the surface of the material being processed. As a t, the productis continuously drawn from the botof the container andforced to passthrough the reed openings in the mixing head where it is submit- 0 highshearing forces. In these experiments, a 1.5 radius rotor with 0.01 inchclearance were used.

.e results set forth below were obtained by shearing )ml. sample of theasphalt flux at elevated temperafor 1 hour in the presence of air,nitrogen dioxide trogen. The results obtained ar given below.

ERSION OF LAGNUNILLAS ASPHALT FLUX BY HIGH SHEARING RATES air or NO; waspassed throu h the asphalt flux at a rate of 1 liter nute (measured at75 F. on er 1 atmosphere pressure). .eonventlonsl stirred air-blowingprocess.

e 500 r.p.m. shear under the experimental conditions corresponds to ashear rate of a bout 8,000 recipro- :conds while the 5,000 r.p.m. isequivalent to about '0 reciprocal seconds. The relationship betweenr.p.m. eciprocal seconds was calculated from the formula:

R 2a'7 N h e R=shear rate in sec.-

r r -r,,,= =mean annulus radius adius of the rotor; r,=radius of stator;N=revoluper second; h=annulus width as estimated. (See VI SpecialTechnical Publication No. 299, covering symposium on Non-NewtonianViscometry, October 1960, pp. 49-60, by F. I. Bonner and J. F. Gyer.)

As is seen from the above data, subjecting as asphalt penetration can beattributed merely to the use of high shearing rates. Thus, run A whereinthe asphalt flux was exposed to an air blanket using low shearing ratesresulted in only a small change in softening point and penetration.However, run B wherein the asphalt flux was exposed to a nitrogenblanket (i.e., no exposure to reactive gas) and a high shearing rateproduced a producthaving a higher softening point and lower penetrationvalue. g

Runs C-H show that higher temperatures produce an even greater effect onsoftening point and penetration which elfect is greatest when nitrogendioxide is passed through the bulk asphalt flux. However, comparing runH with run B it is seen that the use of air-blowing, high temperaturesand moderate shearing rates results in a lower conversion than isproduced by a high shearing rate and a relatively low temperaturewithout the presence of a reactive gas. In other words, vigorousshearing by itself produces an unexpected improvement in the qualitiesof asphalt.

What is claimed is:

1. method for the preparation of asphalts having improved softeningpoint-penetration characteristics, which comprises subjecting apetroleum residuum to shearing at above 4000 reciprocal seconds of shearfor a time suflicient to eifect an increase in the softening point ofthe petroleum residuum.

2. A method according to claim 1 wherein said shearing is conducted at atemprature within the range between about 300 and 600 F.

3. A method according to claim 2 wherein said shear;

v or mixtures thereof.

5. A method according to claim 3 wherein said temperature is within therange between about 400 and 550 F.

6. A method according to claim 5 wherein said shearing force is appliedfor a time sufficient to increase the softening point of the petroleumresiduum at least 40%.

7. A method according to claim 6 wherein said shearing force is withinthe range between about 40,000 and 500,000 reciprocal seconds.

8. A method according to claim 5, 6 or 7 wherein said residuum issheared in the presence of air, nitrogen oxide or mixtures thereof.

9. A method according to claim 8 wherein said shearing force is appliedfor 15 to 30 minutes.

References Cited UNITED STATES PATENTS DELBERT E. GANTZ, PrimaryExaminer V. OK-EEFE, Assistant Examiner

